F-LOOP 3.0 · Loop Antennas
A loop antenna or loop-system component for compact, directional, broadband, receive, or field operation.
Why operators make room for it
Work the bands from a compact, controlled footprint
When available space is tight, antenna geometry and orientation become tools the operator can actively control.
The F-LOOP 3.0 was designed with portability, ease of use simplicity, ruggedness and high performance in mind. Unlike any other similar antennas on the market, the CHA F-LOOP 3.0 is made with premium materials that are precisely manufactured and assembled in the USA!
The result is a deliberate loop-based station that can be positioned, tuned, and re-oriented as conditions change instead of forcing a long-wire solution into the wrong site.
Quick product reference
Key Specifications
- Product type
- Loop Antennas
- Primary role
- A loop antenna or loop-system component for compact, directional, broadband, receive, or field operation.
- Available style
- CHA F-LOOP 3.0 (BASIC KIT)
- CHA F-LOOP 3.0 TOTAL (BOOSTER KIT 4' DIAMETER. LMR 400-RADIATOR)
- CHA F-LOOP 3.0 PLUS (TWO SECTIONS ALUMINUM RADIATOR)
- Frequency
- CHA F-LOOP 3.0 BASIC: Standard Flexible Loop: approximately 4.7 – 29.7 MHz (60 through 10 meter ham bands), Double Flexible Loop: approximately 2.8 – 11.9 MH (80 through 30 meter ham bands), CHA F-LOOP 3.0 PLUS: Rigid Radiator Loop: not measured, but guaranteed 5.4 to 29.7 MHz (60 through 10 meter ham bands). CHA F-LOOP 3.0 TOTAL: Flexible Booster Loop: approximately 4.0 - 23.1 MHz (60 through 15 meter ham bands)
- Power
- 25W intermittent duty cycle (SSB telephony), 10W continuous duty cycle (CW, AM, FM, RTTY, and other digital modes)
- Diameter
- 34 inches (Standard Loop), 48 inches (Booster Loop), 36 inches (Rigid Loop) Ingress Protection: Not water resistant. Equivalent to IP30 (not tested)
- Rf Connection
- UHF Plug (PL-259)
- Color
- Black and Light Gray
- Weight
- 4 lbs
- Personnel Requirements And Setup Time
- one operator, around 2 minutes
- Swr
- Operator tunable, typically not greater than 3.0:1 at resonance. Table (3) shows typical 2:1 bandwidth for the three antenna configurations. Note: The bandwidth of the Rigid Loop was not measured but should be comparable to the Standard configuration. CHA F-LOOP 3.0 BAND 80 60 40 30 20 17 15 12 10 2:1 SWR BANDWIDTH (KHZ)* STANDARD DOUBLE 6 8 12 17 14 27 28 40 60 100 160 210 BOOSTER 16 30 60 90 140 *Bandwidth may vary
- Published package contents
- 1 X F-LOOP 3.0 tuning box
- 2 X LMR-400 coax cable radiators (102" LONG each) (10M - 80M)
- 1 X Dual Female connector
- 1 X 12’ RG-58 Coax with integrated RFI choke feed-line
- 1 X Shoulder Bag
- 1 X Proprietary coupling loop 6.5"
- 1 X Telescopic Mast
- 1 X User guide
- Deployment role
- Loop geometry and tuning are product-guide dependent
- Verification
- Retune and verify after any site or geometry change
Operator decision support
Plan the complete setup
See what this product is best suited for, what the documented setup needs, and the boundaries to confirm before deployment.
- Best for
When available space is tight, antenna geometry and orientation become tools the operator can actively control.
- What’s included
- 1 X F-LOOP 3.0 tuning box
- 2 X LMR-400 coax cable radiators (102" LONG each) (10M - 80M)
- 1 X Dual Female connector
- 1 X 12’ RG-58 Coax with integrated RFI choke feed-line
- 1 X Shoulder Bag
- 1 X Proprietary coupling loop 6.5"
- 1 X Telescopic Mast
- 1 X User guide
- What else you need
- SWR Power Meter
- Heavy-Duty Tripod
- Limitations
Do not use an antenna tuner or coupler; it can cause the loop to be mistuned
- Expansion options
- CHA SS ADAPTER
- CHA JAWMOUNT
- CHA UCM
- CHA SPIKE MOUNT
- CHA POWER COMPENSATOR
- Booster Kit
What an operator can do
- Deploy the loop in the documented shape, orientation, height, and support arrangement.
- Use the specified coupling, tuning, feed-line, and support components for the selected loop configuration.
- Re-check tuning and clearance whenever the loop location or geometry changes.
Complete product details
DISCONTINUED THE F-LOOP 4.0 WILL BE RELEASED LATER IN 2026
The F-LOOP 3.0 Antenna is the newly updated design of our EXTREMELY popular F-LOOP 2.0. It's smaller, lighter and more compact!
The F-LOOP 3.0 was designed with portability, ease of use simplicity, ruggedness and high performance in mind. Unlike any other similar antennas on the market, the CHA F-LOOP 3.0 is made with premium materials that are precisely manufactured and assembled in the USA!
Easily deployable HF magnetic loop antennas, also called small transmitting loops, have been routinely used for many years in military, diplomatic, and shipboard HF communication links, where robust and reliable general coverage radio communication is a necessity.
These antennas have only recently become commercially available for amateur radio. The real practical advantage of the small loop, compared to a short vertical whip tuned against earth or a full sized vertical antenna, is the loop’s freedom from dependence on a ground plane and earth for achieving efficient operation; this unique characteristic has profound significance for portable or restricted space antennas.
In comparison, the bottom of a vertically oriented loop does not need to be more than a loop diameter above ground, making it very easy to install in a restricted space location. There is no significant improvement in sky wave propagation performance when a small loop is installed high; all that matters is the loop is substantially clear of objects in the immediate area and oriented towards the desired direction of radiation.
Field trials of the F-LOOP 3.0 Antenna demonstrated that an indoor magnetic loop antenna was only around one to two S-units lower, on both transmit and receive, than outdoor full size quarter wave vertical antenna. Remarkable for an antenna that is only less than three foot in diameter and covers 3.5 MHz to 29.7 MHz (80 – 10 meter ham bands)!
The magnetic loop is different from typical antennas because it emphasizes the magnetic part of the radio wave (H field) rather than the electric part (E field) of the radio wave. It also has a high Q resonance of around 17 KHz on 40 meters, providing immunity from interference outside the bandpass.
The F-LOOP 3.0 Antenna was designed with weight, portability, versatility and cost in mind and is ideal for RV/camping, hotels, apartments, condominiums, homeowner’s associations, deed restrictions and CCRs (Covenants, Conditions & Restrictions), Shortwave Listening (SWL) and other places where it is not feasible to erect a multi-band wire or vertical antenna.We’re sure you will be amazed by the performance and agree that the F-LOOP 3.0 is the most advanced portable magnetic loop antenna available today.
Specifications:
- 3.5 MHz to 29.7 MHz (80 - 10 meter ham bands)
- Power handling: 25W SSB 10W CW & DIGITAL
- Proprietary solderless aluminum coupling loop. This coupling loop design can be used with any types of coax cable feed-lines. Because of its rigidity, the antenna tuning will remain stable, consistent and will prevent SWR fluctuations due to usual coupling loop deformation.
- The collapsible portable mast allows easy storage, fast deployment and ease of use in all conditions. No need to play with multiple tubular PVC sections to assemble the antenna.
- The 12’ RG-58 feedline with RFI choke decouples the coupling loop from the radio which is essential to prevent SWR fluctuation while rotating the antenna or moving the coax cable around.
- Our custom made capacitors which are equipped with a 6:1 reducer, offer a smooth and consistent tuning while providing the highest efficient performance on the market.
- Shoulder Bag
- Larger Delrin tuning knob for smoother tuning and operation.
- The base of the tuning unit is equipped with an aluminum anodized base plate. That base plate can be placed directly on a flat surface or can be mounted on a tripod with a 1/4x20 thread, or our CHA UCM, or utilizing the 3/8" through hole to our CHA Jawmount or other mounting solution.
The F-LOOP 3.0 BASIC antenna system consists of:
- 1 X F-LOOP 3.0 tuning box
- 2 X LMR-400 coax cable radiators (102" LONG each) (10M - 80M)
- 1 X Dual Female connector
- 1 X 12’ RG-58 Coax with integrated RFI choke feed-line
- 1 X Shoulder Bag
- 1 X Proprietary coupling loop 6.5"
- 1 X Telescopic Mast
- 1 X User guide
The F-LOOP 3.0 TOTAL antenna system consists of:
- 1 X F-LOOP 3.0 tuning box
- 1 X LMR-400 coax cable radiator (146" LONG) (15M to 40M)
- 1 X Proprietary coupling loop 8"
- 2 X LMR-400 coax cable radiators
- 1 X Dual Female connector
- 1 X 12’ RG-58 Coax with integrated RFI choke feed-line
- 1 X Shoulder Bag
- 1 X Proprietary coupling loop 6.5"
- 1 X Telescopic Mast
- 1 X User guide
The F-LOOP 3.0 PLUS antenna system consists of:
- 1 X F-LOOP 3.0 tuning box
- 1 X TWO Sections Aluminum Radiator (10M - 40M)
- 1 X Proprietary coupling loop 7"
- 2 X LMR-400 coax cable radiators
- 1 X Dual Female connector
- 1 X 12’ RG-58 Coax with integrated RFI choke feed-line
- 1 X Shoulder Bag
- 1 X Proprietary coupling loop 6.5"
- 1 X Telescopic Mast
- 1 X User guide
Enhancing the efficiency of a magnetic loop antenna, such as the CHA F-LOOP 3.0, involves optimizing key parameters, notably the conductor (radiator) diameter and the overall loop diameter. Adjustments to these dimensions can significantly impact the antenna's performance.
Conductor (Radiator) Diameter:
The efficiency of a magnetic loop antenna is closely tied to the diameter of its conductor. A larger conductor diameter reduces the antenna's loss resistance, thereby increasing efficiency. This is because a thicker conductor offers a greater surface area, which decreases resistance due to the skin effect at radio frequencies. For instance, replacing a loop made from RG-8A/U coaxial cable (with a conductivity of 4,500,000 mhos/m) with one made from a solid copper tube of the same diameter (conductivity of 58,000,000 mhos/m) can increase radiation efficiency from 10.1% to 36.5%.
Loop Diameter:
Increasing the loop's diameter has a profound effect on efficiency. The radiation resistance of a loop antenna is proportional to the fourth power of its circumference. Therefore, even modest increases in loop diameter can lead to substantial improvements in radiation resistance and overall efficiency. For example, increasing the circumference from 9 feet (~3 ft diameter) to 38 feet (~12 ft diameter) at 7 MHz can boost antenna efficiency from 20% to 95%.
Application to CHA F-LOOP 3.0:
The Chameleon CHA F-LOOP 3.0 antenna system offers modular components that allow users to customize both the conductor and loop diameters:
-
Radiator Options:
- LMR-400 Coaxial Cable: This cable has a diameter of 0.405 inches and is commonly used in the standard configuration of the CHA F-LOOP.
- Two-Section Aluminum Radiator: This option utilizes 1-inch diameter aluminum tubing, providing a thicker conductor compared to the LMR-400 coaxial cable.
-
Loop Diameter Enhancement:
- CHA Booster Kit: This kit expands the loop diameter to 48 inches, increasing the overall circumference of the antenna.
By upgrading from the LMR-400 coaxial cable to the 1-inch aluminum tubing, the conductor's diameter increases, thereby reducing loss resistance and enhancing efficiency. Additionally, using the CHA Booster Kit to enlarge the loop diameter further increases radiation resistance, leading to a more efficient antenna system.
In summary, increasing both the conductor diameter and the loop diameter in a magnetic loop antenna like the CHA F-LOOP 3.0 can significantly improve its efficiency. These modifications reduce loss resistance and increase radiation resistance, resulting in better overall performance.
